Tag: cell-the basic unit of life

Antonie van Leeuwenhoek (1632-1723) described cells in a drop of pond water using a microscope made by him. He was the first person to observe bacteria and protozoa. By observing the movement of bacteria or protozoa he named them animalcules. Therefore, the correct answer is option A.

The size of cells and microorganisms are too small to observe by naked eyes. It was impossible to study them but with the invention of the microscope, cells became visible and many new discoveries were made about them. Therefore, the correct answer is option D.

Cytology is the branch of science which, deals with the study of form, structure, and contents of cells as observed under the microscope. The term was coined by Hertwig in 1893. Cytology has enormous application in genetics, biomedical research etc. It is used for diagnosis and screening of various diseases. It can also be for the study of the genetic composition of a living organism.

Virus are non-living crystallisable entities which replicate in other living cells. They do not have a cellular structure and are an exception to cell theory.

Ribosomes were first seen by Claude in 1941 but first studied by Robinsons and Brown in 1953 in bean root cells. Thus, the correct answer is option D.

Cell biology is a scientific study of the cells. It is concerned with the physiological properties, structure, the organelles it contains, interactions with the environment, life cycle, division and death of the cell. It is associated with the morphological and molecular level of the cell.

Robert Brown discovered the nucleus. He discovered the presence of nucleus in the cells of orchid root. Nucleus is a specialized double membrane bound protoplasmic body which contains all the genetic information for controlling cellular metabolism. 

Robert Hooke was mathematician and physicist. He discovered the cell. He took a piece of spanish oak and prepared thin slice by means of sharp pen knife. A deep planoconcave lens was used for throwing light on cork piece. The latter was observed under the microscope. The piece of cork was found to have a honey comb structure with a number of box like compartments, each having a pore and separated from others by diaphragms. Robert Hooke named the compartments as cellulae, now known as cells.
Nucleus was discovered by Robert Brown. He discovered the presence of nucleus in the cells of orchid root. Nucleus is a specialized double membrane bound protoplasmic body which contains all the genetic information for controlling cellular metabolism and transmission to the posterity.

The majority of cells are small. Normal animal cell size varies from 10 to 30 micrometer, while plant cell stretches from 10 to 100 micron. 

Cells are called the structural and functional unit of life because all the living organisms are made up of cells and also all the functions taking place inside the body of organisms are performed by cells. Cells provide specific conditions, for the occurrence of the metabolic reactions. These have specialized enzymes, which catalyze the biochemical reaction and regulates the functions of the body.